High Volume V/S High Pressure Q\'s.

I would like someone to 'splain to me the dynamics and reasining behind a high volume and a high pressure oil pump.

I have seen it argued on this site that High pressure is diffrent so I need to know this:

My current engine running stock volume OP has 25# hot OP.

I'm good for 5,000 rpms give or take because I hold 50# OP at any rpm above 2,000.

Will a high volume pump or a high pressure pump allow me to spin more RPM's safer?

I know the check valve on a high presure oil pump will bleed off the pressure at a set rate to keep the pressure as constant as this mechanical device can do.

I do not know how a high volume pump works in conjunction with pressure,

Given that the bleed off rate of the oil system remains the same throughout the use of the diffrent types of oil pumps what would the diffrence in pressures work out to with either pump style and which would give me an rpm advantage?


FE
(sorry for being so long winded... Kind of my way about things)
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High volume pumps cam make more pressure at a lower rpm. If they are equipped with a high pressure spring, they will move more oil throughout the engine.

I only use high volume/high pressure pumps. 70 psi is what I consider a good oil pressure for high rpm use in the 460 type engines.

Greg
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Thanks Greg, as you may have seen, I am building my 200 to have as much HP and torque as I can give it with a stock rotating assy. I am in the process of working the head to flow as we speak, and will have this engine close to 200 HP fairly soon.

Anyone else care to give something? (I mean besides cutting off two of the doors and putting a V8 in it... [img]/forums/images/smiles/icon_lol.gif[/img])



FE
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Pressure is regulated by the relief, volume is generally regulated by rotor size.

My opinion is that you need to have bearing clearances right first, to include cam bushings. Then personnaly I like high volume and pressure like Greg, assuming the motor can return the oil to the pan

If it cant return properly, then I restrict to the top end, especially in shaft style setups like the FE.

However, let me add, if you have proper clearances, odds are a stock pump will work fine in even some pretty wild applications
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http://data.melling.com/Tech%20pdfs/HIGHVOLUMEPUMPS.pdf
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A high volume oil pump is more like insurance - it pumps more per revolution, but will generate no more pressure than a standard, unless equipped with a higher rate spring. If you're going to be making power and winding the engine up, it makes sense to have that added oil capacity available. You should be fine if everything was machined correctly, but that extra bit of oil may make the difference.

A high volume pump can also band-aid loose clearances, but certainly will not cure them.

Thanks Scott and Wes, Those two tidbits are what I needed! Great reads.


FE

_________________
I'm so depressed... My doctor refused to write me a prescription for Viagra. He said it would be like putting a new flagpole on a condemned building...

<font size=-1>[ This Message was edited by: FEandGoingBroke on 1/24/07 12:05pm ]</font>

Can't argue with much of anything said here with the exception of using a high pressure pump. This is an item that comes down to personal preference and the kind of clearances that you run in your bearings. Some racers like to have large clearances in their bearings to reduce friction. Then they run heavier oil through a high pressure (and usually a high volume - high pressure) pump. The high pressure pump does require more HP to run it. (Smokey U. thought it was the wrong way to go) I prefer to run a high volume pump with normal clearances and normal weight oils. I use either a scraper or a windage tray to keep the oil off the rotating assembly and in the pan. Some engines use restrictions to keep oil from overloading the top end and that is a good thing to do if you need to do it. When you run large clearances in your bearings it takes higher pressure to maitain an oil film on the bearings. High volume pumps won't do that they will push oil through those clearances at normal pressure until the clearance gets so big that the pump can't keep up and then your pressure starts to drop. A combination pump (high volume and pressure) will move more oil at a higher pressure and is ideal for a large clearance engine. You still need to keep oil from the top end and a scraper or windage tray to get the oil off the rotating mass and back in the pan.
What it comes down to for me is - Do I want (need) to run large clearances in the bearings or am I going to be operating my engine below the RPM that I need the larger clearances? I don't run above 6000 RPM and usually build engines that only run at 5500 to get their max power. I don't need to have those large clearances in that operating range and at normal temperatures. If I was going to build a 1.5 HP per Cu" engine or more than I might want to go to the larger clearances on the bearings and a high pressure, high volume oil pump. So, How fast are you going to turn that 200 of yours? Are you going to be running it on the street or at the track where you expect to slip new bearings in occasionally to freshen the engine? Do you need to run the larger clearnces in your motor or are you going to run the tight bearings that Ford recommends?
It is in your hands.
Paul

I am going to drive it as a dily driver and go to work car. BUt I would like to spin it up to 6K or even way more [img]/forums/images/smiles/icon_smile.gif[/img] THere are 7 main berings in the motor so I have mores resistance in the oil to get from point "A" to the last connecting rod.
Along with that lst rod and bearing I have a lot of strength in this crank to allow a few more rpms and hold the engine together...
I think 6,500 is a goood spin to point, and I'd love to be abble to go to 8,000! But I'm on a budget and just getting a cam for it will set me back further than I want to.

Got a question for you though.

I have a pipe with a 1/4" hole in the end that represents the clearances on my bearings... I can push "X" amount of fluid through it and have "X" amount of pressure, right?
How can I change the Volume of that fluid to a larger volume and NOT increase the pressure in doing so?

I mean if the system holds "X" amount of fluid flow resistance naturally. Wouldn't the Pressures increase if the volume was increased?

Or is there extenuating circumstances to prevent this?


FE
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One more thing to consider.... A high volume/high pressure pump allows you to run external oil filters or an oil cooler (or both) without excessive pressure drops.

In other words, if you run a semi restrictive oil cooler system, but want to se 55 psi at your pressure gauge (assuming the gauge is plumbed in after the cooler, as is usually the case) then a 60 or 70 psi pump will allow for that drop while still giving you plenty of oil volume.

Just as an FYI, I run .0025 on the rods and .003 on the mains...relatively loose clearances, but not excessively so. I also run Valvoline 20w50 racing oil year round (temps rarely get below freezing here in big D). I also run an FL-1HP Ford Racing filter with a higher bypass threshhold.

So, I have some impediments to flow (high filtration filter with a hard to trigger bypass valve) and not much resistance to flow (loose clearances). That means I NEED the higher volume to create pressure, and I need more pressure to overcome the restrictions.

I also run a 9 qt pan. This has worked well up to 700 rpm so far.

It may be a little overkill for something more reasonably street oriented.

However.... I see absolutely NO drawback to overbuilding the oil system. It is cheap insurance.

Greg


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